“Voltec” is the brand name for GM’s revolutionary extended-range electric vehicle (E-REV) technology that uses electricity as its primary power source and gasoline as its secondary power source to generate electricity. The main components of the Voltec electric propulsion system include a T-shaped battery pack, an 111 kW electric drive unit, and an engine generator of electricity.

An E-REV like the Chevrolet Volt represents a significant departure from conventional hybrids. In a E-REV, the wheels are turned by an electric drive unit, whereas in conventional hybrids the wheels are turned by an electric motor, a gasoline engine, or both. For short trips, E-REVs will run on battery power alone. For longer trips, additional electricity can be supplied by an internal combustion engine or a fuel cell. The battery and propulsion systems are sized so that when sufficient energy is available from the battery, the engine (or fuel cell) is not required for operation. During this electric only phase of driving, the battery, motor, and power electronics are designed to deliver full performance, acceleration, top speed, hill climbing on electric power alone.

How Voltec Works

Energy is stored on board in a 16-kWh, “T”-shaped lithium-ion battery pack. The battery pack powers the electric drive unit, which is capable of meeting full vehicle speed and acceleration performance while driving the car electrically for up to 40 miles (64 km) (based on EPA city cycle) without using a drop of gas. For longer trips, the Volt’s on-board range-extending engine is used to drive an electric generator when the battery’s energy has been depleted. The range extender, which can be powered by gas/E85 Ethanol, is able to generate additional electricity to power the car for hundreds of miles.

A new and distinct propulsion system category that would comprehend E-REVs has been proposed by the California Air Resources Board, which GM expects that the Chevrolet Volt will become the first to qualify. Other government agencies are also considering the unique benefits of E-REVs.

Benefits

There are many benefits of an E-REV like the Chevrolet Volt. The main benefits include energy diversification, reduced oil consumption, and reduced emissions.

According to a Society of Automotive Engineers study published by GM in April 2008, an E-REV will consume, on average, less than half of the gasoline compared to a plug-in hybrid and substantially reduce regulated emissions resulting from initial trip starts. According to a 2003 Omnibus Household survey by the U.S. Department of Transportation, nearly 80 percent (76 percent) of U.S. drivers commute 40 miles or less daily.

GM estimates that the Chevy Volt will save about 500 gallons (1,892 liters) of gasoline based on 40 miles of daily driving and 15,000 miles annually. For drivers that commute 60 miles (96 km) per day or 21,000 miles annually, about 550 gallons (2,081 liters) of gasoline could be saved.

As a baseline comparison, GM estimates that the cost per mile to operate an E-REV like the Chevy Volt is approximately two cents per mile electrically versus 12 cents per mile using gasoline priced at $3.60 per gallon.

Not a “hybrid”

In practice, hybrid vehicles typically require both sources – engine and battery – to provide full vehicle performance capability. In a hybrid vehicle, the combustion engine is typically the larger of the two propulsion sources, and provides most of the power during high power vehicle maneuvers like off-line starts and freeway cruising. A plug-in hybrid operates the same way, but can be recharged by plugging in. Even with useful energy in the battery, the engine will often be operating to achieve vehicle peak loads. An E-REV is unique from a hybrid or plug-in hybrid in that the vehicle’s wheels are always driven electrically by an electric drive unit.

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With each Volt purchase you’ll get one of these two chargers – either a portable 120V charging unit that can plug into any outlet in the garage and can also be carried along in the vehicle, or a dedicated 240V unit that will require installation into a more powerful connection, just like a dryer.

Of course, the 240V unit will charge up the Volt quicker than the portable unit, but GM knows that customers will have different needs and so wants to offer options.

the 120V unit has two charge rates. The normal rate is 12 amps, but if this causes circuits to break or other problems in the house, there is a user-selectable 8 amp charge option. The 240V charger has a 16 amp output, which is just over what the Volt’s 16 kWh battery is suited for. The charger has three lights to indicate that the unit is receiving AC power, if there is a fault, like a ground fault circuit interrupter indicator, and whether or not there is a ground present.

The now-standard J1772 connector had plenty of safety features built in. One useful feature: The Volt won’t move if you leave it plugged in. This disabling feature is not dependent on whether there is current coming in or not. The car itself detects if the handle is plugged in, eliminating the possibility of a bright orange tail.

One extra that GM is adding to the J1772 is a flashlight that will light up whenever the release handle is depressed. Water and weather and sunlight won’t be a problem for these chargers, either. Both chargers can be mounted outdoors, if needed, and the female connectors can be dipped in water or sprayed clean.

WARREN, Mich. – The Chevrolet Volt extended-range electric vehicle is expected to achieve city fuel economy of at least 230 miles per gallon, based on development testing using a draft EPA federal fuel economy methodology for labeling for plug-in electric vehicles.

The Volt, which is scheduled to start production in late 2010 as a 2011 model, is expected to travel up to 40 miles on electricity from a single battery charge and be able to extend its overall range to more than 300 miles with its flex fuel-powered engine-generator.

“From the data we’ve seen, many Chevy Volt drivers may be able to be in pure electric mode on a daily basis without having to use any gas,” said GM Chief Executive Officer Fritz Henderson. “EPA labels are a yardstick for customers to compare the fuel efficiency of vehicles. So, a vehicle like the Volt that achieves a composite triple-digit fuel economy is a game-changer.”

According to U.S. Department of Transportation data, nearly eight of 10 Americans commute fewer than 40 miles a day http://tinyurl.com/U-S-DOTStudy .

“The key to high-mileage performance is for a Volt driver to plug into the electric grid at least once each day,” Henderson said.

Volt drivers’ actual gas-free mileage will vary depending on how far they travel and other factors, such as how much cargo or how many passengers they carry and how much the air conditioner or other accessories are used. Based on the results of unofficial development testing of pre-production prototypes, the Volt has achieved 40 miles of electric-only, petroleum-free driving in both EPA city and highway test cycles.

Under the new methodology being developed, EPA weights plug-in electric vehicles as traveling more city miles than highway miles on only electricity. The EPA methodology uses kilowatt hours per 100 miles traveled to define the electrical efficiency of plug-ins. Applying EPA’s methodology, GM expects the Volt to consume as little as 25 kilowatt hours per 100 miles in city driving. At the U.S. average cost of electricity (approximately 11 cents per kWh), a typical Volt driver would pay about $2.75 for electricity to travel 100 miles, or less than 3 cents per mile.

The Chevrolet Volt uses grid electricity as its primary source of energy to propel the car. There are two modes of operation: Electric and Extended-Range. In electric mode, the Volt will not use gasoline or produce tailpipe emissions when driving. During this primary mode of operation, the Volt is powered by electrical energy stored in its 16 kWh lithium-ion battery pack.

When the battery reaches a minimum state of charge, the Volt automatically switches to Extended-Range mode. In this secondary mode of operation, an engine-generator produces electricity to power the vehicle. The energy stored in the battery supplements the engine-generator when additional power is needed during heavy accelerations or on steep inclines.

“The 230 city mpg number is a great indication of the capabilities of the Volt’s electric propulsion system and its ability to displace gasoline,” said Frank Weber, global vehicle line executive for the Volt. “Actual testing with production vehicles will occur next year closer to vehicle launch. However, we are very encouraged by this development, and we also think that it is important to continue to share our findings in real time, as we have with other aspects of the Volt’s development.”